
import java.util.Scanner;

class OVERF09 {

    static Scanner entrada = new Scanner(System.in);

    public static void main(String[] args) {
        int N = entrada.nextInt();
        int P = entrada.nextInt();
        char C = entrada.next().charAt(0);
        int Q = entrada.nextInt();

        if (C == '+') {
            System.out.println((P + Q) > N ? "OVERFLOW" : "OK");
        } else {
            System.out.println((P * Q) > N ? "OVERFLOW" : "OK");
        }
    }
}
